The proposed research program brings behavioral, cognitive, and neurobiological methodology to bear on the problem of optimizing mentally retarded individual's abilities to use their limited attentional skills. Working in the domains of visual discrimination, distribution of visual attention, immediate and delayed memory, skill acquisition, five laboratories will undertake in depth, goal oriented investigations, aimed at determining conditions which permit subjects to maximize their performance in these areas. We hope to devise improved ways of (1) assisting concept formation and generalized performance in immediate and delayed matching-to-sample, (2) mitigating overselectivity of perception, and (3) optimizing learning by adjusting task related variables. The laboratories will also deploy variants of their paradigms of interest for use in monitoring change over time in cognitive efficiency due to early onset dementia in Down Syndrome. Down patients will be followed longitudinally to document their neurological and cognitive status. We expect to (1) develop refined tools for early detection of the onset of dementia, and (2) better delineate its effect on cognitive processes.